In their basic form, disposable absorbent articles comprise an absorbent core interposed between a pervious body-contacting element (alternatively referred to as a topsheet or an overwrap) and an impervious protective barrier (alternatively referred to as a backsheet). The absorbent element is, of course, intended to receive and contain the fluids discharged from the body. The body-contacting element is intended to provide comfortable and dry-feeling contact with body surfaces while allowing free passage of fluids therethrough into the absorbent element. The protective barrier is intended to prevent the fluids which are expelled or which escape from the absorbent element from soiling the user's garments.
In addition to the three functional elements mentioned above, disposable absorbent articles are generally provided with means for supporting the device adjacent the user's crotch area, even as the user moves, where it can most effectively perform its intended function. Typically, absorbent articles as sanitary napkins are provided with an adhesive attachment means for securing the device to the inner crotch area of the user's undergarments.
Improved fluid interception can occur if the absorbent article is in close contact with the body of the wearer.
While previously known absorbent articles perform their intended function, each conventional design can be further improved in one or more of absorbency of body fluids, protection of the user's garments from soiling, and/or physical comfort to the user.
With respect to disposable sanitary napkins several attempts have been made in the art to improve body contact with the wearer, and hence absorb fluids upon discharge and thereby minimize soiling by providing a sanitary napkin having an anatomically shaped configuration, particularly including those that are raised upwardly or humped in their medial portions so as to be near or in contact with the pudendal region when worn.
On female users these sanitary napkins attempt to contact and absorb menses immediately as it leaves the vestibule.
Some articles have been also described in which an anatomically shaped configuration is provided during the wearing time, with the advantage of a better fit to the anatomy.
According to U.S. Pat. No. 3,512,530 a sanitary napkin is described in which a compressed regenerated cellulose sponge layer is combined with a larger fibrous cellulose layer to form a multiple ply absorbent core. The compressed regenerated cellulose sponge layer is positioned over the fibrous layer, and it is typically centered about it; it is intended as the primary absorbent element of the sanitary napkin, while the fibrous layer acts as a secondary or back up absorber.
The sanitary napkin may be therefore very thin prior to use, as compared to other sanitary products having the same absorbent capacity.
Although the compressed regenerated cellulose sponge layer is capable of expanding in Z-direction upon fluid absorption, the structure described is not particularly suitable to provide an effective body contact with the wearer's anatomy and might cause discomfort to the user due to the characteristics of the compressed regenerated cellulose sponge material, particularly when it is dry.
EP Patent 293 208 B1 describes the use of multiple layers of compressed regenerated cellulose sponge sheets in a sanitary napkin as the sole absorbent material instead of the usual cellulose pulp absorbent core in order to obtain an absorbent article of improved strength and shape retainability in wet conditions, as compared to traditional absorbent articles with fluff cores that tend to be broken or to form lumps in use.
The sheets are provided with slits in order to enhance their flexibility, with a better comfort for the user, and to increase the fluid absorbing area.
The sanitary napkin described in the EP patent 293 208 B1 has a structure that is not specifically intended to provide a self shaping capability during the use taking advantage of the swelling of the absorbent material, but rather a better strength when wetted than articles using conventional, fluff-based absorbent cores, and a better flexibility and absorbency rate as compared to articles using the same compressed regenerated cellulose sponge material.
U.S. Pat. No. 3,736,931 discloses a sanitary napkin having an outer non-compressed layer of fluid absorbent material and an inner core of highly compressed fluid absorbent material which is at least partially enclosed therein. The napkin preferably is V-shaped in cross section and is arch-shaped in its longitudinal direction by die compression. When the napkin is worn the fluid directs first into the inner compressed layer so as to cause it to swell and to expand the outer non-compressed layer in all directions, thereby adjusting itself to each wearer.
The sanitary napkin expands upon fluid absorption and may adjust itself to the user's anatomy, but since it is not flat prior to use it may be cumbersome to package and to handle; moreover, the expansion takes place mainly in the lateral direction, thus achieving an effective seal against the inner side of the thighs and at both sides of the vaginal orifice; therefore the structure is neither capable of forming a convex upward configuration nor does it bring the absorbent element in direct contact with the point of release of the fluid.
Therefore there is still the need for an absorbent article capable of providing an anatomically shaped configuration for a closer body contact which is achieved during the use upon activation by absorbed body fluids, while it is comfortable for the wearer and easy to produce and to package.